Schalke released Ghana midfielder Kevin-Prince Boateng and Germany winger Sidney Sam on Monday with immediate effect, while suspending Marco Hoeger, as their latest defeat threatens next season's place in Europe.

With one win in their last eight games, the Royal Blues' 2-0 defeat at Cologne on Sunday left Roberto di Matteo's Schalke sixth in the league.

They are in danger of missing out on a Europa League berth next season having reached the last 16 of the Champions League this year.